revert "kill" command to previous 7.0 behavior

[sfc-gh-etschannen]

because the current implementation is killing processes one at a time

cherry pick of #7149

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[foundationdb-ci]

AWS CodeBuild CI Report for Linux CentOS 7

• CodeBuild project: foundationdb-pr
• Commit ID: a428054
• Result: FAILED
• Error: Error while executing command: ninja -v -C build_output -j ${NPROC} all packages strip_targets. Reason: exit status 1
• Build Logs (available for 30 days)

[fdb-windows-ci]

Doxense CI Report for Windows 10

• Commit ID: a428054
• Result: ❌ FAILED
• Build Logs (available for 30 days)

[fdb-windows-ci]

Doxense CI Report for Windows 10

• Commit ID: 8b295a6
• Result: ❌ FAILED
• Build Logs (available for 30 days)

[foundationdb-ci]

AWS CodeBuild CI Report for Linux CentOS 7

• CodeBuild project: foundationdb-pr
• Commit ID: 8b295a6
• Result: FAILED
• Error: Error while executing command: ninja -v -C build_output -j ${NPROC} all packages strip_targets. Reason: exit status 1
• Build Logs (available for 30 days)

[fdb-windows-ci]

Doxense CI Report for Windows 10

• Commit ID: 314e219
• Result: ✔️ SUCCEEDED
• Build Logs (available for 30 days)

[foundationdb-ci]

AWS CodeBuild CI Report for Linux CentOS 7

• CodeBuild project: foundationdb-pr
• Commit ID: 314e219
• Result: SUCCEEDED
• Error: N/A
• Build Logs (available for 30 days)